If you're healthy and eating a balanced diet, your body controls how much fat it burns, and you don't normally make or use ketones. But when you cut way back on your calories or carbs, your body will switch to ketosis for energy. It can also happen after exercising for a long time and during pregnancy. For people with uncontrolled diabetes, ketosis is a sign of not using enough insulin.
As for branched-chain amino acids, you'll find smart people who swear that they're keto-friendly, and others who don't. One of the BCAAs, valine, can be glucogenic, meaning that it can lead to glucose production and potentially contribute to leaving ketosis behind.[1] But does that mean it will happen? Not necessarily, particularly if you're just an occasional supplement user.
Normal body cells metabolize food nutrients and oxygen during cellular “respiration”,  a set of metabolic pathways in which ATP (adenosine triphosphate), our main cellular energy source is created. Most of this energy production happens in the mitochondria, tiny cell parts which act as powerhouses or fueling stations. There are two primary types of food-based fuel that our cells can use to produce energy:

If you’re looking to get a jump start on your health and fitness goals this year, you may be thinking about trying the ketogenic diet. Maybe you’ve heard the phrase before — it’s a huge diet buzzword — but aren’t sure what it means. Here’s a primer: The ketogenic diet is an eating plan that drives your body into ketosis, a state where the body uses fat as a primary fuel source (instead of carbohydrates), says Stacey Mattinson, RDN, who is based in Austin, Texas.
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